The invention relates to convertible ladders and is more particularly of the type which is convertible to either an extension ladder or a step ladder and can also be used as a hand truck or dolly.
Convertible devices utilizable selectively as either a ladder or a hand truck or dolly have been known heretofore. U.S. Pat. No. 2,980,200 issued Apr. 18, 1961 to W. A. Kibby shows one such structure whereas U.S. Pat. No. 3,104,889 issued Sept. 24, 1963 to C. R. Branch, Jr. discloses another such structure. However, typical of the prior art devices of this character the structures are not utilizable as extension ladders, the overall length of the device when used as a handtruck limiting the ladder height. Of particular difficulty also, apparently, is the convertability of such structures into either a step ladder or an extension ladder.